Research is proposed in the following areas: 1. Thermodynamic studies will be continued on the factors which affect in vitro self-assembly of pure brain tubulin into microtubules and other structures. Particular attention will be devoted to non-tubulin proteins which may complex with tubulin and to ligands, specifically calcium and GTP. 2. The mechanism of chymotrypsin self-association will be pursued further by sedimentation equilibrium studies of various derivatives along the pathways of activation. 3. The mechanism of protein stabilization and crystallization by solvent components will be pursued further with the application of thermodynamic multicomponent theory. In particular, glycerol, MPD, and DMSO will be examined.